1. Field of the Invention
This invention relates to conveyor systems of the type having a conveying belt trained around spaced guide rollers for movement in a predetermined travel path. More particularly, the invention is directed to a support system for a roller which bears supportingly against the conveying belt.
2. Background Art
Conveyor systems are used in a wide range of applications and in many diverse environments. In a typical conveyor system, a conveying belt is trained around spaced head and tail pulleys/rollers for continuous movement in a predetermined travel path. In a portion of the travel path, the conveying belt defines an upwardly facing supporting surface upon which articles/materials can be placed to transport the same from a loading location to another location, as dictated by the system configuration. Typically, the articles/materials will separate from the conveying belt at the location of the head roller for appropriate disposition, such as by transfer to another conveyor system for movement to yet another location. A significant expanse may exist between the head and tail pulleys/rollers. The unsupported belt, traveling in the return, underside, path portion is commonly borne supportingly upon by one, or a plurality of, rollers, commonly designated “idler rollers”.
It is common to construct conveyor systems with sufficient space beneath the conveying belts for individuals to traverse. This type of system presents two potentially dangerous situations. First of all, the conveying belt, moving in the return path portion at each idler roller, creates a pinch point. The advancing conveying belt and each idler roller are advanced in the same general direction and converge to a pinch point. Inadvertent contact by anyone with the conveying belt at the return path portion, upstream of an idler roller, could draw a contacting limb or digit dangerously into the pinch point. The industry has long been aware of this problem. A number of guards have been designed to reduce the risk of injury at each idler roller location.
One such guard system blocks the converging geometry upstream of the pinch point. While a guard of this type addresses potential injury, it also introduces another operating problem. The guard system defines an obstruction that intercepts material that has not been cleaned from the conveying belt as it passes through the return path portion. This condition may eventually lead to the impairment of the system operation, particularly when the conveyed material is a particulate that has a tendency to bind. This condition may be aggravated by severe conditions in which the conveyor system operates, whereby the conveyed material is dampened and is resultingly bonded with greater tenacity to the conveying belt. This type of material may follow the conveying belt into its return path portion so that it progressively accumulates at the guard system to a point that the conveying belt movement and/or idler roller operation may be affected. This accumulation of material may also be sufficient that the idler roller may be forced to disengage from its operative position.
Conventional idler rollers have had a tendency to separate from their mounts in conveyor systems. These rollers may have a significant weight that could inflict injury upon anyone who is contacted by them. The industry has also been aware of this problem for some time. This has led to the development of certain guard systems which are designed to prevent potentially dangerous, unrestricted downward travel, of idler rollers that have disengaged from their operative positions.
One example of such a guard system is shown in U.S. Pat. No. 6,318,545 (Ross, II). Ross II has a trough-shaped element placed over each idler roller. In the event of separation, the idler roller will be intercepted and confined by the trough-shaped element.
Ross II also discloses structure for wiping the underside of the blade on both the upstream and downstream ends of the guard. This avoids the migration of foreign matter carried on the conveying belt into the receptacle defined by the trough-shaped element. However, it is inevitable that there will be some material that does find its way past the upstream wiper and into the roller receptacle bounded by the trough-shaped element. This progressive accumulation could ultimately fill the receptacle, which could block the movement of the idler roller and also potentially cause the entire roller mechanism, including the guard, to disengage from its support.
Another problem associated with these guard systems is that they must generally be designed for a specific roller configuration. That is, the “trough” that is defined generally is designed to optimally perform with a specific diameter of idler roller. Thus, these guard systems must each be designed and inventoried for use with a specific idler roller configuration. By reason of having to inventory different sizes of guard systems, inherently expenses are increased in terms of both a) manufacture and stocking and b) handling preparatory to sale.
Another problem with the fixed configuration guard systems is that they are generally made from metal materials for purposes of maintaining their integrity, even in harsh operating environments. Construction using metal is generally relatively expensive. Additionally, metal parts are prone to corrosion, particularly in environments in which conveying belts are commonly operated. That is, conveying systems are often operated in an exterior environment in which they are exposed to moisture, due to rain, snow, and/or high humidity. Further, the conveyed materials are also often corrosive to metal. If not monitored, the metal components in the guard systems may deteriorate to the point that they fail under the weight of a disengaged idler roller, whereby an operator is exposed to not only the danger of the falling idler roller, but the components of the guard systems.
Still further, metal components, while durable, are heavier than most of their non-metal counterparts. In overhead systems, installation of the guard system may be difficult and time consuming, by reason of the weight of certain components and/or the overall system.
There is currently underway a campaign by governing bodies in this industry to require guards to prevent personal injury in the vicinity of the idler rollers resulting from the above condition. Designers in this industry continue to seek ways to address safety issues without impairing the basic operation of the conveyor systems.